1. Field of the Invention
The present invention relates to a base station apparatus used in a CDMA-based radio communication system and its code assignment method.
2. Description of the Related Art
A CDMA-based base station apparatus (hereinafter simply referred to as xe2x80x9cbase stationxe2x80x9d) presets code specification information specific to each apparatus, generates codes based on this code specification information and transmits signals multiplied by those codes. The code specification information is code phase for a PN code, etc. and code type for a Walsh code, etc.
In a conventional method of assigning codes to base stations, code specification information is fixedly assigned through advance theoretical design to base stations preventing them from interfering with one another.
However, if a new base station is added, the conventional method of assigning codes to base stations above has a problem of having the necessity of repeating theoretical design to assign codes to all base stations once again.
It is an objective of the present invention to provide a CDMA base station apparatus and code assignment method that will not require theoretical design to assign codes to all base stations even if a new base station is added.
The present invention achieves the objective above by reading stored code specification information and measuring its interference level, selecting code specification information whose interference level is smaller than a preset threshold as its own code information candidate and determining the code specification information of the station from the selected code specification information.